The invention relates in general to a cutting insert for a ball end mill, and in particular, to a double-sided cutting insert for a ball end mill having four cutting edges that can cut in any direction without the requirement of error proofing when the cutting insert is mounted on the ball end mill.
Ball nose end mills are used in many metal working applications including mold making where the inherent strength and milling advantages of a fully radiused cutting edge for the copy milling of a mold cavity is best demonstrated. Its ball shape allows the end mill to attack the mold cavity from any angle or direction. The cutting edge when generated through the end of the ball mill becomes helical with rotation. This promotes shearing of the metal to be cut in an efficient manner.
A conventional ball nose end mill includes a generally cylindrical end mill body having a generally hemispherical forward end portion. Two insert-receiving seats or recesses are formed in the forward end portion, diametrically opposite to each other. Two indexable cutting inserts are mounted in the two seats and secured thereto by means of clamp screws.
Ball nose end mills have proven to be highly versatile machine tools that are capable of performing plunge-type cutting much like a drill, or face-type milling like a conventional milling head, or even ramp-type machine operations that combine the motions of both plunge and face-type cutting. However, the cutting inserts used in conventional ball end mills have at most two cutting edges on one side of the cutting insert with the other side used strictly as a seating surface. As a result, one-half of the cutting insert is not being used, which increases the overall operating cost of such a conventional end mill.